scholarly journals cis/trans Isomerization rate of oxazolam in organic solvents measured by high-performance liquid chromatography.

1989 ◽  
Vol 37 (4) ◽  
pp. 1044-1046 ◽  
Author(s):  
Yukihisa KURONO ◽  
Yasuhiro JINNO ◽  
Tomonari KUWAYAMA ◽  
Naomi SATO ◽  
Tamotsu YASHIRO ◽  
...  
2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
John E. A. Carter ◽  
Patrick M. Sluss

This study examined the effects of ionic strengths of NaCl (0.1, 0.3, and 1.0 M), pH (3, 7, and 11), and organic solvents (dichloromethane, diethyl ether, and methanol) on the extraction of estradiol at concentrations of 5.0 pg/mL in human serum. Methanol extracted almost 100% of the estradiol at a 5.0 pg/mL concentration, while ether and dichloromethane extracted only 73% or 70%, respectively, of the estradiol. The methanol extracted material was subjected to reverse phase high-performance liquid chromatography (HPLC) using 60% methanol and was found to elute at the same position as estradiol standard. These results suggest that methanol extraction of estradiol may prove useful in situations where estradiol occurs at concentration levels of ≥5.0 pg/mL, concentrations of great clinical significance in the detection and treatment of breast cancer.


Author(s):  
E.B. Markova ◽  
A.S. Savchenko ◽  
A.G. Cherednichenko ◽  
Yu.M. Averina ◽  
V.S. Boldyrev

The paper studies the process of analysis of tetracycline and paracetamol with the use of the HKUST-1 organometallic framework sorbent by high performance liquid chromatography. To obtain experimental data using the previously described technique, a sample of the material under consideration was synthesized and its physicochemical properties were studied. It has been established that individual sorbent particles have an octahedral shape and have a porous structure capable of adsorbing chemical compounds of various nature. The specific surface of the sample was calculated using the BET method and was Ssp = 551.3 m2/g. The study notes that when water or aqueous-organic media are used as eluents for chromatographic analysis, sorbents based on HKUST-1 have low stability; their degradation is observed when passing eluent solutions in an amount equal to 300--500 volumes of the chromatographic column. When only organic solvents are used for chromatographic analysis of tetracycline and paracetamol in the temperature range of 25--45 °C, no decomposition of the HKUST-1 sorbent and no degradation of the analyzed drugs are observed. Findings of research show that the efficiency of the eluent increases in the tetrahydrofuran--methanol--acetonitrile series. For all organic solvents used, the retention times were determined, the degree of separation, HETP, and the speed of response were calculated at various temperatures. A complex of studies has proved the possibility of using the organometallic sorbent HKUST-1 for the effective separation of drug mixtures by high-performance liquid chromatography


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